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Air Force Pamphlet 11-238 17 March 2011 Flying Operations Aircrew Quick Reference to the METAR and TAF Codes ACCESSIBILITY: Pu ublications and forms...
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Air Force Pamphlet 11-238 17 March 2011 Flying Operations

Aircrew Quick Reference to the METAR and TAF Codes

ACCESSIBILITY: Pu ublications and forms are av vailable on the e-Publishing website at www.e-Publishing.af.mil for downloading or ordering. RELEASABILITY: There are no releasability restrictions on this publication. OPR: AFFSA/A3OF Supersedes AFPAM 11-238, 1 Nov 05

Certified by: HQ USAF/A3O-B (Mr. Steven Pennington) Pages: 36

Introduction The Aircrew Quick Reference Guide to the METAR and TAF Codes helps aircrews quickly and clearly translate METAR and TAF codes into plain language. See Attachment 1 for a list of source documents. METAR reports are observed weather conditions while the TAF indicates forecast conditions. Both are lines of text made up of coded data groups separated by spaces. Some groups are not discussed because they are only intended for use by the weather community. Differences between military and civilian renderings of the code are discussed. Aircrews should always check METAR and TAF reports thoroughly for all hazards to flight safety and other elements that may affect aircraft performance or mission accomplishment. When users have weather-related questions, they should contact a certified US military forecaster or MAJCOM-approved weather source for clarification. Weather briefing requirements for USAF Aircrews are spelled out in AFI 11-202, Volume 3, General Flight Rules. Refer recommended changes and questions about this publication to the Office of Primary Responsibility (OPR) using the AF Form 847, Recommendation for Change of Publication; route AF Form 847s from the field through the appropriate functional’s chain of command. This publication may not be supplemented. SUMMARY OF CHANGES This document includes clarifications of METAR sector visibility and vertical visibility and removes references to runway surface conditions (now reported via NOTAMs). It also incorporates several changes to the TAF format, specifically: repositioning the AMD and COR modifiers for emphasis, adding a ―prepared/disseminated‖ time group to military TAFs (already included in civilian TAFs), reformatting of the TAF valid time groups, noting that some civilian TAFs are valid for up to 30 hours, and adding a ―T‖ before both maximum and minimum temperature groups in military TAFs.

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Table of Contents Section I, METAR decoding: Report Type Location and Date/Time Auto/Cor Wind Wind Variability Visibility Runway Visual Range Type of Weather Clouds Temperature/Dewpoint Altimeter Setting Remarks, US Remarks, Overseas Section II, TAF decoding: Report Type Location Date/Time Time and Type of Change Expected Wind Visibility Type of Weather Clouds Wind Shear Icing Turbulence Minimum Altimeter Setting Temperatures

Page 4 5 6 7 8 9 10 11 13 14 15 16 17 Page 19 20 21 22 23 24 25 26 27 28 29 30 31

Figures 1. Weather/Obscuration Table - METAR/TAF 2. Remarks Decode Table - METAR 3. Icing Intensity Decode Table - TAF 4. Turbulence Intensity Decode Table - TAF Attachments 1. Glossary of References and Supporting Information 2. Temperature Conversion, Fahrenheit to Celsius 3. Reportable Visibility Conversion, Statute Miles to Meters 4. Runway Visibility Conversion 5. Pressure Conversion, Millibars to Inches

Page 12 18 28 29 Page 32 33 34 35 36

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METAR

Report Type

What kind of report is this? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 This report is a METAR (roughly translated from French as Aviation Routine Weather Report)—a scheduled observation normally taken between 50-59 minutes past the hour (also referred to as a routine hourly observation). A METAR can be distinguished from a TAF by its single date/time group. SPECI KBLV 011715Z 25015G30KT 210V290 3SM BR BKN015 01/M01 A2984 RMK SLP034 SPECI (Aviation Selected Special Weather Report) refers to an unscheduled report taken when certain criteria have been met (such as a change from VFR to IFR) and may be taken anytime.

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METAR

Location and Date/Time

How do I determine the location and the date and time of issuance? PAAQ 011657Z AUTO 25015G30KT 210V290 3/8SM BKN005 03/M01 A2984 RMK A02 SLP034 KCLK 291012Z AUTO 08009KT 2SM -RA SCT005 OVC009 M01/M01 A2999 RMK AO2 The 4-character ICAO identifier is the location; PAAQ (Palmer Municipal) and KCLK (Clinton Regional) are the locations/stations in these examples. The 7-character group following the ICAO identifier is the date and time of issuance. The first two digits are the date; the last four digits are the coordinated universal time (UTC), sometimes called ―zulu time.‖ In the first example, 01 is the 1st day of the month, and 1657Z is 1657 UTC. The second example takes place on the 29th day of the month at 1012 UTC. When ICAO identifiers are not available or cannot be used, a 4-character identifier starting with KQ will be used. This practice is normally found in a contingency environment, where the location/identifier combination is often classified. Consult the local weather flight for more details.

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METAR

AUTO/COR

What does AUTO and/or COR mean, if included? Let’s look at the meanings of AUTO and COR separately. KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02A SLP034 AUTO refers to an automated observation with measurements taken by equipment such as the domestic Automated Weather Observing System (AWOS) or Automated Surface Observation System (ASOS), or the Air Force’s Automated Meteorological Station (AMS), also known as AN/FMQ-19. AO1 denotes an observation taken by equipment lacking a precipitation type discriminator (rain vs. snow). AO2 denotes an observation taken by standard equipment with a full complement of sensors. A02A denotes an automated observation augmented by a human observer. Absence of these indicators denotes a manual report by a human observer. KBLV 011657Z AUTO COR 25015G30KT 210V290 3/8SM R32L/1000FT FG FU BKN005 01/M01 A2984 RMK A02A SLP034 COR 1725 COR indicates a corrected observation. Disregard the previous transmission. COR 1725 means that the correction was transmitted at 1725Z.

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METAR

Wind

How do I determine the wind speed and direction? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 The data group followed by KT (knots) is the wind. The first three digits are the true direction to the nearest 10 degrees from which the wind is blowing. The next two digits are the sustained speed. If gusts are present, the next two or three digits following the ―G” are the ―gust,‖ the maximum wind speed in the last ten minutes. In this example, the 25015G30KT group is the wind direction and speed. Here, the wind is blowing from 250 degrees (true) at a sustained speed of 15 knots, gusting up to 30 knots. Calm wind is encoded as 000000KT.

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METAR

Wind Variability

How do I determine if the wind is varying between directions? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 A wind variability group will be reported if the wind is variable by 60 degrees or more and the speed is greater than 6 knots. This remark will contain the extremes of the wind directions, separated by ―V.‖ In the example above, 210V290 reads, ―wind direction varying between 210 and 290.‖ KBLV 011657Z AUTO VRB03KT 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 VRB is used (without direction extremes) when the wind speed is less than or equal to 6 knots. In the example above, VRB03KT reads, ―wind direction is variable at 3 knots.‖

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METAR

Visibility

How do I determine the prevailing visibility? KBLV 011657Z 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK SLP034

Visibility is measured in statute miles. In this example, 3/8SM (3/8 of a statute mile) is the prevailing visibility. Prevailing visibility is the greatest horizontal visibility observed throughout at least half the horizon circle, not necessarily continuous. Surface visibility is measured at a point six feet above ground level. Sector visibility may be reported in the remarks section if it differs from the prevailing visibility and is less than 3 miles, or otherwise considered operationally significant. For sector visibility format, see VIS remarks in Figure 2 on page 18. EDDF 071320Z 22008KT 9999 SCT036 SCT090 BKN280 19/10 Q1011 NOSIG

Most overseas locations report visibility in meters and omit the SM identifier. The largest reportable metric value is 9999. This value represents a visibility greater than 9000 meters (7 SM or more). The contraction CAVOK (ceiling and visibility OK) may be used when there is no significant weather, the visibility is 10 km or greater, and the ceilings are greater than 5,000 ft. To convert visibility values from meters to statute miles see Attachment 3 or the Flight Information Handbook conversion tables.

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METAR

Runway Visual Range, “R”

What if there is a group that begins with the letter “R?” KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 Runway Visual Range (RVR) follows the visibility and begins with the letter ―R.‖ The runway heading will follow the ―R,‖ and in this example, ―32L‖ represents runway 32-Left (C-Center, R-Right). The last four digits report the visibility in feet. In this example, R32L/1000FT reads, ―runway visual range for runway 32 Left is 1,000 ft.‖ Most overseas locations report visibility in meters and omit the FT identifier from the RVR group. The same RVR at an overseas location would appear as R32L/0300 and read, ―runway visual range for 32 Left is 300 meters.‖ How would I decode the formats M0600FT or P6000FT or R06L2000V4000FT (not in example above)? M0600FT P6000FT R06L2000V4000FT

Reads, ―RVR is less than 600 feet.‖ (M = less than) Reads, ―RVR is greater than 6,000 feet.‖ (P = greater than) Reads, ―RVR for 6 Left is variable between 2,000 and 4,000 feet.‖ ―V‖ indicates that the RVR is variable between two thresholds.

For RVR conversion charts, see Attachment 4 or the front section of any Instrument Approach Procedures (IAP) booklet. 10

METAR

Type of Weather

How do I determine if there is any weather? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 If a weather element (precipitation or obstruction to visibility) is observed, it will be found in the data group following the visibility. The absence of a weather element group indicates that no precipitation or obstruction to visibility is occurring at the time of the observation. In this example, ―FG‖ represents ―Fog.‖ To methodically decode a weather group, look for six key elements (depending on the phenomena, one or more may be omitted). In order, these elements are: Intensity (symbol preceding the code), Proximity, Descriptor, Precipitation Description, Obscuration (other than precipitation), and Other. For a complete table of weather group elements and examples, see Figure 1 on page 12, or reference Section C ―METAR and TAF Code‖ of the Flight Information Handbook.

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METAR

Weather/Obscuration Table

Figure 1. Weather/Obscuration Table Phenomenon Qualifiers Element 1: Intensity

-

Element 2: Proximity

none

Light

VC

none Moderate

DSNT

+

Element 3: Description

On station

BC

Patches

In the vicinity (5-10 miles) > 10 miles

BL

Blowing

DR FZ MI PR

Low Drifting

Heavy

Note: + can also mean a well-developed dust storm, sandstorm, whirl, dust devil, tornado, or waterspout

SH TS

Freezing Shallow Partial (covering part of the sky) Shower(s) Thunderstorm

Types of Weather Phenomenon Element 4: Precipitation

DZ Drizzle GR Hail, diam. ≥ 5mm (.25") GS Small Hail / Snow Pellets, diam. < 5mm (.25") Ice Crystals Ice Pellets Rain Snow Grains

IC PL RA SG SN Snow UP Unknown Precipitation

Element 5: Obscuration Mist, vis. ≥ 5/8SM

BR DU FG FU HZ PY SA VA

(or ≥ 1000m) Widespread Dust Fog, vis. < 5/8SM (or ≥ 1000m) Smoke Haze Spray

Element 6: Other

DS Dust Storm FC Funnel cloud(s) e.g., tornado or waterspout

PO Well-developed dust/sand whirls

SQ Squalls SS Sandstorm

Sand Volcanic Ash

(Automated only)

Examples: +SHRASNPL TSRAGS BR HZ BCFG PRFG

heavy rain showers, snow, ice pellets thunderstorm, moderate rain, small hail mist (vis. >= 5/8SM), haze patchy fog (vis. < 5/8SM) partial fog (sector vis. < 5/8SM)

+DRSN VCSH FZDZ BLPY +DS

heavy snow, drifting showers in vicinity freezing drizzle blowing spray heavy dust storm

A similar table can be found in Section C of the Flight Information Handbook. 12

METAR

Clouds

How do I determine the layers of clouds? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 Each observed cloud layer is encoded in a cloud group with sky coverage, altitude of the cloud base above ground level (AGL), and sometimes cloud type. The first three letters of each cloud group denote sky coverage as in the table below. In this example, BKN indicates broken cloud coverage. To interpret the reported cloud base, append two zeros to the value given. In this example, 005 represents the value 500 feet AGL. Finally, in augmented or manual observations, codes for convective cloud types may be appended. CB stands for cumulonimbus; TCU stands for towering cumulus. If surface-based obscurations (e.g., clouds, smoke, haze) are reported, and the lowest broken or overcast cloud base cannot be determined, then vertical visibility in hundreds of feet determines the ceiling. For example, VV002 represents a vertical visibility of 200 feet. Sky coverage in eighths: SKC or CLR Sky clear FEW Few (Trace – 2/8) SCT Scattered (3/8 – 4/8) BKN * Broken (5/8 – 7/8) OVC * Overcast (8/8) * The lowest layer reported as broken or overcast constitutes a ―ceiling‖

A similar table can be found in Section C, ―METAR and TAF Code‖, of the Flight Information Handbook. 13

METAR

Temperature/Dewpoint

How do I determine the current temperature and dewpoint? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 The group following the sky condition is the temperature and dewpoint information in degrees Celsius. To convert temperatures from Celsius to Fahrenheit see Attachment 2 or the Flight Information Handbook conversion tables. In this example, 01 is the temperature in degrees Celsius (1ºC), and M01 is the dewpoint in degrees Celsius (-1ºC). An ―M‖ in the temperature or dewpoint field means ―minus‖ (below zero).

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METAR

Altimeter Setting

How do I determine the current altimeter setting? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 The 5-character group beginning with A, following the temperature/dewpoint group is the altimeter setting in inches and hundredths of an inch of mercury (inches Hg), used in the United States and at US airfields overseas. In this example, A2984 represents a current altimeter setting of 29.84 inches Hg. EDDF 071320Z 22008KT 9999 SCT036 SCT090 BKN280 19/10 Q1011 NOSIG The 5-character group beginning with Q, following the temperature/dewpoint group is the altimeter setting in hectopascals (hPa), used at most overseas locations. A hectopascal is equivalent to a millibar (mb). In this example, Q1011 represents a current altimeter setting of 1011 hPa or 1011 mb. To convert altimeter settings from mb (or hPa) to inches Hg, see Attachment 5 or the Flight Information Handbook conversion tables.

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METAR

Remarks, US

What is RMK? KBLV 011657Z AUTO 25015G30KT 210V290 3/8SM R32L/1000FT FG BKN005 01/M01 A2984 RMK A02 SLP034 In METAR reports from the United States and from overseas US military airfields, RMK indicates the start of the Remarks section. Remarks contain any pertinent information beyond the standard fields provided and can be either encoded or spelled out in plain language. For a partial listing of possible METAR remarks, see Figure 2 on page 18. Additional abbreviations are constructed in accordance with FAA Order 7340.1, Contractions. In this example, the remark, SLP034, is the sea level pressure in millibars (or hectopascals) to the nearest tenth. To decode, place a ―10‖ or ―9‖ before the first digit (use a 9 if the 3-digit value is 500 or more), and place a decimal point before the last digit. The sea level pressure remark in the above example would read ―current sea level pressure of 1003.4 millibars.‖ Caution: Do not confuse the METAR remarks ―5####‖ group or ―6####‖ group with the TAF ―5######‖ (turbulence) group or the TAF ―6######‖ (icing) group. Unlike TAF code usage, METAR ―5‖ and ―6‖ group codes indicate pressure tendency and cumulative precipitation amounts--if you need these values, contact your weather provider for decoding instructions. See pages 28 and 29 for more info on decoding TAF icing and turbulence forecasts.

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METAR

Remarks, Overseas

What is supplemental information? Overseas (except at US military installations), METAR remarks are called ―supplemental information.‖ Supplemental information follows the altimeter setting and uses remark codes like US remarks, as in Figure 2 on page 18, but is not preceded by RMK. Supplemental information can also include: - Recent weather elements, coded with a leading RE - Sea surface temperature in ºC and sea state 0-9, coded W##/S# - Runway state, coded as an 8-digit numerical group - A 2-hour forecast trend as described below EDDF 071320Z 22008KT 9999 SCT036 SCT090 BKN280 19/10 Q1011 NOSIG Overseas METAR forecast trend groups either start with BECMG or TEMPO, consistent with TAF coding conventions, or they consist entirely of NOSIG, which indicates that no significant changes in reportable weather elements are expected during the 2 hours following the reported observation. METARs issued by North Atlantic Treaty Organization (NATO) observers have, as the last data group, a color code for ceiling and visibility data: NATO Airfield Weather Color Code. source: AFMAN 15-111 USAFESUP1 Color Code Color * Ceiling at or above: Visibility at or above: BLU blue 2500 feet 8000 meters WHT white 1500 feet 5000 meters GRN green 700 feet 3700 meters YLO yellow 300 feet 1600 meters AMB amber 200 feet 0800 meters RED red < 200 feet < 0800 meters Airfield not useable for reasons other than BLACK black ceiling or visibility * Belgium, France, Netherlands, and United Kingdom use scattered clouds instead of ceiling

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METAR

Remarks Decode Table

Figure 2. Remarks Decode Table A01 – Reported by automated observation equipment that CANNOT distinguish between rain and snow A02 – Reported by automated observation equipment that CAN distinguish between rain and snow ACC W – AltoCumulus Castellanus clouds West ACSL SW-S – AltoCumulus Standing Lenticular clouds SouthWest through South ALSTG/SLP ESTMD– Estimated Pressure. Primary airfield sensors are suspect or inoperative; backup equipment is being used. CB W MOV E – CumulonimBus clouds West MOVing East CBMAM DSNT S – CumulonimBus MAMmatus clouds to the DiStaNT South CCSL OVR MT E – CirroCumulus Standing Lenticular clouds OVeR MounTain(s) to the East

PK WND 34050/38 – PeaK WiND 340 at 50 knots occurred at 38 minutes past the hour PRESRR / PRESFR – PRESsure Rising Rapidly / PRESsure Falling Rapidly RAB20SNB20E55 – RAin and SNow Began at 20 minutes past the hour, Ended at 55 min past RVRNO – RVR-equipped, but NO report SFC VIS 2 1/2 – SurFaCe VISibility is 2 ½ statute miles; remarked when (lower) tower visibility is reported in METAR body SLP015 – Sea Level Pressure is 1001.5 millibars TCU OHD – Towering CUmulus clouds OverHeaD TCU W – Towering CUmulus clouds to the West TSB05E30 – ThunderStorm Began at 05 minutes past the hour and Ended at 30 min past TWR VIS 1 – ToWeR VISibility is 1 statute mile; remarked when (lower) surface visibility is reported in METAR body VIRGA – VIRGA at the station; precipitation observed but not reaching the ground VIRGA DSNT NE – VIRGA to the DiStaNT NorthEast VIRGA SW – VIRGA to the SouthWest

CONS LTGCA – CONtinuouS (more than 6 flashes per minute) LighTninG, Cloud to Air

VIS 1V2 – VISibility is Variable between 1 and 2 miles

FROPA – … due to FROntal Passage

VIS 2 RWY 11 – VISibility is 2 statute miles at RunWaY 11

FRQ – FReQuent (1-6 flashes per minute for lightning) LTGCA – LighTninG, Cloud to Air LTGCC – LighTninG, Cloud to Cloud LTGCG – LighTninG, Cloud to Ground LTGIC – LighTninG, In-Cloud OCNL – OCcassioNaL (less than 1 flash per minute for lightning)

VIS N 2 – VISibility in the Northern sector is 2 statute miles WND DATA ESTMD – Estimated Wind. Primary airfield sensors are suspect or inoperative; backup equipment is being used. WSHFT45 – Wind SHiFT at 45 minutes past the hour

PK WND 28045/1955 – PeaK WiND 280 at 45 knots occurred at 1955Z

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TAF

Report Type

What type of report is this? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

This report is a TAF (Terminal Aerodrome Forecast)—a weather forecast at an airport or military base for a specific period. A TAF is distinguished from a METAR by its multiple date/time groups. AMD KBLV 051820Z 0518/0612 21015KT 0800 TSRA BKN008CB QNH2958INS BECMG 0518/0519 29008KT 1600 -RA OVC030 QNH2958INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/18Z TM01/11Z AMD 1820

AMD (Amended Aerodrome Forecast) is issued because the previous version is no longer representative of the current or expected weather. The amended TAF supersedes the previous TAF. In the above example, AMD 1820 indicates that the forecast was amended at 1820Z. Always refer to the date/time group at the end of the TAF to determine the most current forecast. AMD KBLV 051925Z 0518/0612 21015KT 0800 TSRA BKN008CB QNH2958INS BECMG 0518/0519 29008KT 1600 -RA OVC030 QNH2958INS BECMG 0520/0521 18015KT CAVOK QNH2950INS T08/18Z TM01/11Z COR 1925

AMD is also used with COR (Corrected Aerodrome Forecast) to indicate that a TAF has been corrected. When a corrected TAF is issued, disregard previous TAFs. In the above example, COR 1925 indicates that the amended forecast was corrected at 1925Z. Always refer to the date/time group at the end of the TAF for the most current forecast. 19

TAF

Location

How do I determine the location? PAAQ 041419Z 0414/0512 VRB03KT 6SM BR OVC003 TEMPO 0414/0418 5SM BR FM042000 34005KT P6SM FEW008 SCT070 KCLK 081126Z 0812/0912 07009KT 3SM -SN BR OVC003 FM082100 05008KT 1SM -SN BR OVC001

The 4-character ICAO identifier is the location. PAAQ (Palmer Municipal) and KCLK (Clinton Regional) are the locations/stations in these examples. When ICAO identifiers are not available or cannot be used, a 4character identifier starting with KQ will be used. This is usually in a contingency environment, and the location/identifier combination is often classified. Consult the local weather flight for more details.

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TAF

Date/Time

How do I determine the date and valid times of the forecast? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z KPVU 081123Z 0812/0906 32009KT P6SM OVC050 TEMPO 0812/0816 SCT050 FM081600 VRB04KT P6SM SCT200 KSLC 081123Z 0812/0918 35007KT P6SM BKN120 FM090400 15005KT P6SM SCT200 FM090900 14004KT P6SM SCT120 BKN200

The next two groups that follow the ICAO identifier show the preparation/dissemination time of the TAF and the valid time of the forecast. In the KBLV (Scott AFB) example, 051151Z shows that the TAF was prepared/disseminated on the 5th day of the month at 1151Z. The valid time of the forecast follows as 0512/0612 and indicates that the forecast valid time is from 1200Z on the 5th day of the month to 1200Z on the 6th day. Although most TAFs are forecasted for a 24-hour period, the valid times may vary, up to a maximum of 30 hours. For example, the TAF at KPVU (Provo Municipal) is only valid from 1200Z on the 8th day until 0600Z on the 9th day, while the TAF at KSLC (Salt Lake City International) is valid from 1200Z on the 8th day until 1800Z on the 9th day.

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TAF

Time and Type of Change Expected

How do I determine the time and type of changes that will occur? KSTL 051130Z 0512/0612 14008KT 5SM BR BKN030 WS010/18025KT TEMPO 0513/0516 1 1/2SM BR FM051600 16010KT P6SM NSW SKC BECMG 0522/0524 20013G20KT 4SM SHRA OVC020 PROB40 0600/0606 2SM TSRA OVC008CB BECMG 0606/0608 21015KT P6SM NSW SCT040 Civilian and military forecasters alike encode the time and type of change expected with TEMPO, FM, and BECMG groups. TEMPO represents a temporary condition. In this example, TEMPO 0513/0516 1 1/2SM BR reads, ―Temporary condition between 1300Z and 1600Z on the 5th day of 1 1/2 statute mile visibility in mist.‖ Only the temporary changing conditions are included in TEMPO groups. FM means ―from‖ and indicates a rapid weather change where all data groups in the previous line are superseded. In this example, FM051600 reads, ―From 1600Z on the 5th day…‖. BECMG means ―becoming‖ or a ―gradual change‖ in meteorological conditions and becomes the predominant group by the end time listed. In this example, BECMG 0522/0524 reads ―Becoming from 2200Z to 2400Z on the 5th day.‖ PROB40 (civilian use only) represents a 40% probability or chance of conditions occurring along with associated weather conditions (wind, visibility, sky conditions). In this example, PROB40 0600/0606 2SM TSRA 0VCOO8CB reads, ―40% chance between 0000Z and 0600Z on the 6th day of visibility 2 statute miles in moderate thunderstorms, 800 overcast cumulonimbus clouds.‖ 22

TAF

Wind

How do I determine the wind speed and direction? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

The data group after the valid time and followed by KT (knots) is the forecast wind speed. The first three digits within a wind group are the true direction to the nearest 10 degrees from which the wind will blow. The next two digits are the sustained speed. If gusts are forecasted, the next two or three digits following the ―G‖ are the ―gust,‖ the maximum wind speed in a ten-minute window. In this example, 14005KT, 16010KT, 21015G30KT, 29008KT, 31012G22KT, and 30008KT are the wind direction and speed groups. In the first wind group, the wind is forecasted to blow from 140 degrees (true) at a sustained speed of 05 knots. No gust is forecasted. In the third wind group, the wind is forecasted to blow from 210 degrees (true) at a sustained speed of 15 knots, gusting up to 30 knots.

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TAF

Visibility

How do I determine the forecast visibility? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

In the military and at most overseas locations, visibility is forecasted in meters. The 4-character group following the wind is the forecast visibility. In the KBLV example, 8000, 3200, 1600, 3200, and 9999 are the forecast visibilities in meters. 9999 is the greatest value forecasted. A value of 9999 indicates a forecast visibility of greater than 9000 meters (7 statute miles or greater). To convert visibility values from meters to statute miles, see Attachment 3 or the Flight Information Handbook conversion tables. Overseas locations may use the contraction ―CAVOK‖ (ceiling and visibility OK) when there is no significant weather, the visibility is 10 km or greater, and the ceilings are greater than 5,000 ft. KSTL 051130Z 0512/0612 14008KT 5SM BR BKN030 WS010/18025KT TEMPO 0513/0516 1 1/2SM BR FM051600 16010KT P6SM NSW SKC BECMG 0522/0524 20013G20KT 4SM SHRA OVC020 PROB40 0600/0606 2SM TSRA OVC008CB BECOMG 0606/0608 21015KT P6SM NSW SCT040

In the CONUS, civilian TAFS forecast visibility in statute miles up to 6 statute miles, beyond which P6SM is used to indicate forecast visibility greater than 6 statute miles.

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TAF

Type of Weather

How do I determine if there is any forecast weather? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

The weather data group (forecast precipitation or obstruction to visibility) follows the visibility data group. In this example, BR means ―mist,‖ -SHRA means ―light rain showers,‖ TSRA means a ―thunderstorm with moderate rain,‖ and -RA means ―light rain.‖ NSW (no significant weather) is used to indicate that the weather or obscuration listed in the previous group is no longer expected to occur. Absence of a weather or obscuration group means that no weather or obscuration is expected during the forecast period. To methodically decode a weather group, look for six key elements (depending on the phenomena, one or more may be omitted). In order, these elements are: Intensity (symbol preceding the code), Proximity, Descriptor, Precipitation Description, Obscuration (other than precipitation) and Other. For a complete table of weather group elements and examples, see Figure 1 on page 12, or reference Section C, ―METAR and TAF Code‖, of the Flight Information Handbook.

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TAF

Clouds

How do I determine the layers of forecast clouds? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0520/0521 30008KT 9999 SKC QNH2950INS T08/0518Z TM01/0611Z

Cloud height is forecasted in hundreds of feet. Add two zeros to the end of the value given. In this example, FEW030, BKN008CB, OVC020, and SKC represent the values 3,000 few, 800 broken cumulonimbus, 2,000 overcast, and sky clear. Overseas locations may use the contraction CAVOK (ceiling and visibility OK) when there is no significant weather, the visibility is 10 km or greater, and the ceilings are greater than 5,000 ft. In place of cloud layers, vertical visibility in hundreds of feet will appear in a TAF cloud group when the sky is forecast to be totally obscured. For example, VV002 represents a vertical visibility of 200 feet. Vertical visibility in a TAF represents the forecast ceiling. When a surface-based partial obscuration is forecasted, it will be encoded as FEW000, SCT000, or BKN000 in the cloud layer area. A remark will appear after the altimeter that will describe the phenomena responsible. For example, FG SCT000 would indicate the weather element causing the obscuration is caused by fog and the layer amount is SCT. Surface-based partial obscurations will not be considered a ceiling. Sky coverage (eighths): SKC or CLR FEW SCT BKN OVC

Sky clear Few (Trace – 2/8) Scattered (3/8 – 4/8) * Broken (5/8 – 7/8) * Overcast (8/8)

* The lowest layer reported as broken or overcast constitutes a ―ceiling‖ A similar table can be found in Section C, ―METAR and TAF Code‖, of the Flight Information Handbook. 26

TAF

Wind Shear

How do I determine if wind shear is in the forecast? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

A wind shear group is included if non-convective low-level winds (up to 2,000 feet) will change in speed and/or direction and result in a shearing action. WS indicates forecast wind shear and is followed by a 3-digit height in hundreds of feet AGL, a slant character, ‖/,‖ and forecast wind at the height indicated. WS010/18040KT reads, ―forecast wind shear at 1,000 feet above the station; wind at 1,000 feet is from 180 degrees (true) at 40 knots.‖ The remark WSCONDS is used to indicate the potential for wind shear when there is not enough information available to reliably predict the height, direction and speed of the wind shear. WSCONDS is normally used beyond the first 6 hours of the TAF. For some locations, the wind shear group will follow the minimum altimeter setting group (in the TAF remarks) instead of following the cloud group.

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TAF

Icing

How do I determine forecast icing conditions? KBLV 051153Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS T08/0518Z TM01/0611Z

If forecasted, the icing group will be prefixed by the number 6, and follows the cloud group. To decode, follow these instructions: 1. Find the icing designator ―6‖ following the cloud group (620304). 2. The next digit gives icing type and intensity (620304). See Figure 3. 3. The next three digits give the base of the icing layer in hundreds of feet (620304). 4. The last digit provides the icing layer depth in thousands of feet (620304), so add this value to the base height to determine the top limit of the icing conditions. In the above example, the icing forecast will read, ―light rime icing (in cloud) from 3,000 to 7,000 feet.‖ Figure 3. Icing Intensity Decode Table CODE DECODE 0 Trace Icing or None (see note) 1 Light Mixed Icing 2 Light Rime Icing In Cloud 3 Light Clear Icing In Precipitation 4 Moderate Mixed Icing 5 Moderate Rime Icing In Cloud 6 Moderate Clear Icing In Precipitation 7 Severe Mixed Icing 8 Severe Rime Icing In Cloud 9 Severe Clear Icing In Precipitation Note: Air Force code ―0‖ means a trace of icing, World Meteorological Organization code ―0‖ means no icing 28

TAF

Turbulence

How do I determine forecast turbulence conditions? KBLV 051153Z 0512/0612 14005KT 8000 FEW030 QNH2960INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 520004 QNH2952INS T08/0518Z TM01/0611Z

If forecasted, the turbulence code will be prefixed by the number 5, and will follow the cloud or icing group. To decode, follow these instructions: 1. Look for the turbulence designator ―5‖ that follows the cloud or icing group (520004). 2. The next digit will determine the intensity (520004). See Figure 4. 3. The next three digits will determine the base limit of the turbulence layer in hundreds of feet AGL (520004). 4. The last digit will determine the turbulence layer depth in thousands of feet (520004), so add this value to the base height to determine the top limit of the turbulence conditions. In the above example, the turbulence forecast will read, ―occasional moderate turbulence in clear air from the surface to 4,000 feet.‖ Figure 4. Turbulence Intensity Decode Table CODE

DECODE

0 1 2 3 4 5 6 7 8 9 X

None Light turbulence Moderate turbulence in clear air, occasional Moderate turbulence in clear air, frequent Moderate turbulence in cloud, occasional Moderate turbulence in cloud, frequent Severe turbulence in clear air, occasional Severe turbulence in clear air, frequent Severe turbulence in cloud, occasional Severe turbulence in cloud, frequent Extreme turbulence

Note:

Occasional is defined as occurring less than 1/3 of the time

29

TAF

Minimum Altimeter Setting

How do I determine the forecast lowest altimeter setting? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

Forecast minimum altimeter settings are only found in military forecasts. These are near the end of the line, beginning with QNH (minimum) and ending with INS (inches). To convert altimeter settings from inches Hg to hectopascals (millibars), use Attachment 4 or the Flight Information Handbook conversion tables. In the example shown above, QNH2960INS, QNH2959INS, QNH2958INS, QNH2952INS, and QNH2950INS are read as minimum altimeter settings of 29.60, 29.59, 29.58, 29.52, and 29.50 inches of mercury, respectively.

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TAF

Temperatures

How do I determine the forecast temperatures? KBLV 051151Z 0512/0612 14005KT 8000 BR FEW030 WS010/18040KT QNH2960INS BECMG 0513/0514 16010KT 3200 -SHRA OVC020 QNH2959INS TEMPO 0514/0516 21015G30KT 1600 TSRA BKN008CB OVC020 BECMG 0516/0517 29008KT 3200 -RA OVC030 620304 QNH2958INS BECMG 0518/0519 31012G22KT 9999 NSW SCT040 WSCONDS 520004 QNH2952INS BECMG 0520/0521 30008KT CAVOK QNH2950INS T08/0518Z TM01/0611Z

Forecast temperatures for the forecast period are routinely found only in military TAFs. They are found on the last line, following the minimum altimeter, beginning with the designator ―T,‖ maximum temperature first. To convert temperature units from Celsius to Fahrenheit, use Attachment 2 or the Flight Information Handbook conversion tables. In this example, T08/0518Z indicates a forecast maximum temperature of 8°C on the 5th day at 1800Z, and TM01/0611Z indicates a forecast minimum temperature of -1°C on the 6th day at 1100Z.

HERBERT J. CARLISLE, Lt Gen, USAF DCS, Operations, Plans, and Requirements

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Attachment 1 GLOSSARY OF REFERENCES AND SUPPORTING INFORMATION References AFMAN 15-111, Surface Weather Observations AFMAN 15-124, Meteorological Codes ICAO Document 8896AN/893/4, Manual of Aeronautical Meteorological Practice, ISBN 92-9194-345-2 AFMAN 15-111 USAFESUP1, United States Air Forces in Europe Supplement to Surface Weather Observations FAA Order 7340.1, Contractions

Abbreviations and Acronyms AGL—Above Ground Level FAA—Federal Aviation Administration ICAO—International Civil Aviation Organization METAR—Aviation Routine Weather Report NATO—North Atlantic Treaty Organization RVR—Runway Visual Range SPECI—Aviation Selected Special Weather Report TAF—Terminal Aerodrome Forecast UTC—Coordinated Universal Time, sometimes called ―zulu time‖

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Attachment 2 TEMPERATURE CONVERSION Degrees Fahrenheit to Degrees Celsius ºF

ºF

ºF

ºF

ºC

From

To

ºC

From

To

ºC

From

To

ºC

128.3 130.0

54

83.3

85.0

29

38.3

40.0

04

-4.8

-3.1

M20

126.5 128.2

53

81.5

83.2

28

36.3

38.2

03

-6.6

-4.9

M21

124.7 126.4

52

79.7

81.4

27

34.7

36.2

02

-8.4

-6.7

M22

122.9 124.6

51

77.9

79.6

26

32.9

34.6

01

-10.2 -8.5

M23

121.1 122.8

50

76.1

77.8

25

32.0

32.8

00

-12.0 -10.3 M24

119.3 121.0

49

74.3

76.0

24

31.2

31.9 M00 -13.8 -12.1 M25

117.5 119.2

48

72.5

74.2

23

29.4

31.1 M01 -15.6 -13.9 M26

115.7 117.4

47

70.7

72.4

22

27.6

29.3 M02 -17.4 -15.7 M27

113.9 115.6

46

68.9

70.6

21

25.8

27.5 M03 -19.2 -17.5 M28

112.1 113.8

45

67.1

68.8

20

24.0

25.7 M04 -21.0 -19.3 M29

110.3 112.0

44

65.3

67.0

19

22.2

23.9 M05 -22.8 -21.1 M30

108.5 110.2

43

63.5

65.2

18

20.4

22.1 M06 -24.6 -22.9 M31

106.7 108.4

42

61.7

63.4

17

18.6

20.3 M07 -26.4 -24.7 M32

104.9 106.6

41

59.9

61.6

16

16.8

18.5 M08 -28.2 -26.5 M33

103.1 104.8

40

58.1

59.8

15

15.0

16.7 M09 -30.0 -28.3 M34

101.3 103.0

39

56.3

58.0

14

13.2

14.9 M10 -31.8 -30.1 M35

99.5 101.2

38

54.5

56.2

13

11.4

13.1 M11 -33.6 -31.9 M36

97.7

99.4

37

52.7

54.4

12

9.6

11.3 M12 -35.4 -33.7 M37

95.9

97.6

36

50.9

52.6

11

7.8

9.5

M13 -37.2 -35.5 M38

94.1

95.8

35

49.1

50.8

10

6.0

7.7

M14 -39.0 -37.3 M39

92.3

94.0

34

47.3

49.0

09

4.2

5.9

M15 -40.8 -39.1 M40

90.5

92.2

33

45.5

47.2

08

2.4

4.1

M16 -42.6 -40.9 M41

88.7

90.4

32

43.7

45.4

07

0.6

2.3

M17 -44.4 -42.7 M42

86.9

88.6

31

41.9

43.6

06

-1.2

+0.5 M18 -46.2 -44.5 M43

85.1

86.8

30

40.1

41.8

05

-3.0

-1.3

From

To

33

M19 -48.0 -46.5 M44

Attachment 3 REPORTABLE VISIBILITY CONVERSION Statute Miles (SM) to Meters (m) STATUTE MILES 0 1/16 1/8

METERS 0000 0050 0100 0150 0200

STATUTE MILES 1-1/8 1-1/4 1-3/8

METERS 1800 1900 2000 2100 2200

STATUTE MILES 2-3/4 3

METERS 4400 4500 4600 4700 4800

3/16

0250 0300

1-1/2

2300 2400

-

4900 5000

¼ 5/16

0350 0400 0450 0500

1-5/8 1-3/4

2500 2600 2700 2800

4 5 6

6000 7000 8000 9000

3/8

0550 0600

1-7/8

2900 3000

7 8

9999 9999

-

0650 0700

2

3100 3200

9 10

9999 9999

½

0750 0800

-

3300 3400

11 12

9999 9999

5/8 -

0900 1000 1100

2-1/4 -

3500 3600 3700

13 14 15

9999 9999 9999

¾ 7/8 1 -

1200 1300 1400 1500 1600 1700

2-1/2 -

3800 3900 4000 4100 4200 4300

20 25 30 35 40 Etc.

9999 9999 9999 9999 9999 9999

Double underline marks a change in increment 34

Attachment 4 RUNWAY VISIBILITY CONVERSION RVR IN STATUTE NAUTICAL HUNDREDS METERS MILES MILES OF FEET 12 1/4 * 2/10 370 16 1/4 2/10 490 3/10 20 3/8 610 4/10 24 1/2 730 6/10 32 5/8 970 7/10 40 3/4 1220 8/10 45 7/8 1370 9/10 50 1 1520 1-1/10 60 1-1/4 1830

* Helicopter Only

35

KILO METERS .4 .5 .6 .7 1.0 1.2 1.4 1.5 1.8

Attachment 5 PRESSURE CONVERSION Millibars (mb)* to Inches of Mercury (inches Hg) _ _ _0 _ _ _1 _ _ _2 _ _ _3 _ _ _4 _ _ _5 _ _ _6 _ _ _7 _ _ _8 _ _ _9 094_ 27.76 27.79 27.82 27.85 27.88 27.91 27.94 27.96 27.99 28.02 095_ 28.05 28.08 28.11 28.14 28.17 28.20 28.23 28.26 28.29 28.32 096_ 28.35 28.38 28.41 28.44 28.47 28.50 28.53 28.56 28.59 28.61 097_ 28.64 28.67 28.70 28.73 28.76 28.79 28.82 28.85 28.88 28.91 098_ 28.94 28.97 29.00 29.03 29.06 29.09 29.12 29.15 29.18 29.21 099_ 29.23 29.26 29.29 29.32 29.35 29.38 29.41 29.44 29.47 29.50 100_ 29.53 29.56 29.59 29.62 29.65 29.68 29.71 29.74 29.77 29.80 101_ 29.83 29.85 29.88 29.91 29.94 29.97 30.00 30.03 30.06 30.09 102_ 30.12 30.15 30.18 30.21 30.24 30.27 30.30 30.33 30.36 30.39 103_ 30.42 30.45 30.47 30.50 30.53 30.56 30.59 30.62 30.65 30.68 104_ 30.71 30.74 30.77 30.80 30.83 30.86 30.89 30.92 30.95 30.98 105_ 31.01 31.04 31.07 31.10 31.12 31.15 31.18 31.21 31.24 31.27

* A millibar (mb) is equal to a hectopascal (hPa)

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